1. Field of the Invention
The present invention relates to a tape applying device of a box sealing machine, more particularly one, which can prevent boxes from caving in when the boxes are moved through the device in sequence at a high speed for adhesive tapes to stick thereon.
2. Brief Description of the Prior Art
To save labor and time, factories usually use box sealing apparatuses to seal upper openings of boxes after products are positioned in the boxes. A common box sealing apparatus includes upper and lower tape applying devices, which are used to apply adhesive tapes to a pair of upper shutters, and a pair of lower shutters respectively.
Shown in FIGS. 5 and 6 is a tape applying device of a box sealing apparatus, which was developed by the inventor of the present invention, and includes a pair of plates (a1) and (a2), a front pressing wheel mechanism (a3) interposed between and joined to front ends of the plates (a1) and (a2), a rear pressing wheel mechanism (a4) interposed between and joined to rear ends of the plates (a1) and (a2), a cutting mechanism (a5) to sever an adhesive tape, several rollers (a6) to guide the adhesive tape, and a connecting rod (a8) pivoted to both the front and the rear pressing wheel mechanisms (a3) and (a4). The adhesive tape is passed over a front pressing wheel of the front pressing wheel mechanism (a3). When a box is conveyed through the tape applying device, the front pressing wheel will be pressed against the box in order for the adhesive tape to stick to the box. At the same time, a rear pressing wheel of the rear pressing wheel mechanism (a4) will also be pressed against the box to help to make the adhesive tape stick to the box closely. The cutting mechanism (a5) has a cutter (a51), which will swing downwards rapidly to sever the adhesive tape as soon as the box is moved away from the tape applying device. Furthermore, the plate (a2) has a smaller size than the plate (a1) such that a gap (a7) is provided on the tape applying device to face the front pressing wheel mechanism (a3), the cutting mechanism (a5), and the rollers (a6). Consequently, the front pressing wheel mechanism (a3), the cutting mechanism (a5), and the rollers (a6) are exposed to allow the technicians/operators to eliminate hitches/set an adhesive tape/observe operation of the tape applying device with ease.
Referring to FIG. 7 as well, the connecting rod (a8) and the front pressing wheel mechanism (a3) are connected to extension springs (a9); thus, when a box is passed through the tape applying device, the front pressing wheel mechanism (a3) will be forced to retreat by the box, and make the adhesive tape stick to the box. At the same time, the front pressing wheel mechanism (a3) will make the rear pressing wheel mechanism (a4) retreat through the connecting rod (a8). However, because the front pressing wheel mechanism (a3) is connected to the extension springs (a9), it will exert a reacting force on the box, which can cause the box to cave in, when the box is moved onto the front pressing wheel mechanism (a3). Consequently, appearance of the box is spoiled, and the adhesive tape can't stick on the box closely. And, boxes have to be moved through the tape applying device at a relatively low speed, otherwise a large proportion of the boxes will cave in. In other words, the factory isn't allowed to speed up the box sealing apparatus in order to increase output per unit of time.
In addition, because the extension springs (a9) of the connecting rod (a8) have a great length and diameter, the distance between the plates (a1) and (a2) is relatively big in order for the extension springs (a9) to move smoothly. Therefore, the tape applying device can't be used with those boxes that have a small breadth.